Cylinder head arrangement for a piston compressor

ABSTRACT

The invention concerns a cylinder head arrangement for a piston compressor, particularly a hermetically enclosed refrigerant compressor, with a suction muffler and a valve package having a valve plate, at least one suction valve and at least one discharge valve. It is endeavoured to simplify the assembly. For this purpose, the suction muffler has a housing, in which the valve package is adopted, the housing having positioning means, which determine the position of the valve package in the housing.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is entitled to the benefit of and incorporatesby reference essential subject matter disclosed in German PatentApplication No. 102 44 565.6 filed on Sep. 25, 2002.

FIELD OF THE INVENTION

[0002] The invention concerns a cylinder head arrangement for a pistoncompressor, particularly a hermetically enclosed refrigerant compressor,with a suction muffler and a valve package having a valve plate, atleast one suction valve and at least one discharge valve.

BACKGROUND OF THE INVENTION

[0003] A cylinder head arrangement of this kind is known from, forexample, DE 199 15 918 C2. Here, the refrigerant gas is sucked inthrough a pipe, which is or can be connected with the suction muffler. Acylinder head cover is fitted on the valve plate by way of a sealing.The valve plate is fitted on the cylinder block of the compressor by wayof an additional sealing. Neighbouring parts have an alignmentarrangement, so that the best possible overall alignment between theindividual parts can be achieved. However, the costs of fitting such acylinder head are relatively large.

[0004] DE 36 45 083 C2 and DE 199 23 734 C2 show suction mufflers forhermetically enclosed compressors, which are assembled of severalhousing parts. The housing parts are welded together.

[0005] The invention is based on the task of simplifying the assembly ofthe cylinder head arrangement.

SUMMARY OF THE INVENTION

[0006] With a cylinder head arrangement as mentioned in theintroduction, this task is solved in that the suction muffler has ahousing, in which the valve package is adopted, the housing havingpositioning means, which determine the position of the valve package inthe housing.

[0007] Thus, the valve package is placed in the suction muffler. Thishas two advantages. The positioning means position the valve package sothat openings in the valve package and openings in the housing of thesuction muffler can be brought in conformity with each other with a highaccuracy. Additionally, the suction muffler is able to muffle noises,which occur in the valve package. In many cases, this noise mufflingexceeds the mere damping of oscillations in the suction gas. Forexample, the housing can have the shape of a bowl.

[0008] Preferably, the suction muffler is arranged between the valvepackage and a cylinder head cover. This enables a relatively compactembodiment of the cylinder head arrangement. Further, with thisplacement, it is possible to use the housing, which is usually made of aplastic material with poor heat conductivity, as a thermal isolatorbetween the cylinder head cover and the valve package. The cylinder headcover comprises a cavity, into which the discharge gas is supplied.After the compression, the discharge gas has an increased temperature,which is transferred to the inside of the compressor shell via thecylinder head cover, which should, for this purpose, have the bestpossible heat conductivity. The intermediate position of the housing,however, means that heat is no longer transferred direct from the hotcylinder head cover to the valve package.

[0009] Preferably, the housing has an outer limiting wall and acovering, which has a recess, in which the cylinder head cover isarranged. In the circumferential direction, the cylinder head cover isthus, at least on part of its height, surrounded by the suction muffler.Thus, it is possible to provide the suction muffler with the desiredvolume, without increasing the dimensions of the cylinder headarrangement excessively.

[0010] Preferably, the recess has a bottom, which is provided with anopening, through which the valve package is connected with a cavityformed on the inside of the cylinder head cover. Thus, it is possible tofeed the discharge gas from the valve package into the cavity withoutsignificant obstacles.

[0011] Preferably, the cylinder head cover has an outer diameter, whichis smaller than the inner diameter of the recess. Thus, it is possibleto keep the cylinder head cover in contact with the housing merely via abearing area. A contact between the housing and the cylinder head coveron the circumference of the cylinder head cover can be avoided. Thus,the heat transfer from the cylinder head cover to the housing isimpeded.

[0012] Preferably, an inner limiting wall, which surrounds the valvepackage, extends from the covering. Thus, the muffling volume of thesuction muffler is arranged between the outer limiting wall and theinner limiting wall. In the other direction, the muffling volume islimited by the covering and a cylinder block, on which the housingrests. The inner limiting wall surrounds the valve package and retainsit. As the inner limiting wall can be adapted relatively exactly to theouter dimensions of the valve package, a highly exact positioning of thevalve package in the suction muffler can be achieved in a simple manner.

[0013] Preferably, the inner limiting wall extends from the bottom ofthe recess. Thus, it is possible to position the valve package on theside of the opening opposite to the cylinder head cover. The cylinderhead cover then forms the continuation of the stack, which is formed bythe valve package.

[0014] Preferably, in the direction of a compressor block, the innerlimiting wall projects less than the outer limiting wall, the coveringbeing so flexible that also the inner limiting wall can be brought torest on the compressor block by means of a clamping arrangement. Withthis simple measure, it is possible to bring the muffling volume to restwith both the inner limiting wall and the outer limiting wall on thecompressor block with a sufficient tightness, without redundantgeometric determination of the resting points. The resting of the innerlimiting wall on the compressor does not occur until the housing of thesuction muffler is fixed. This gives a good sealing of the muffler.

[0015] Preferably, the outer limiting wall is provided with a sealing,which is meant to rest on the compressor block. This sealing can bemoulded direct on the end face of the outer limiting wall in the form ofa lip seal. It can also have the form of a loose component. It is alsopossible to use a planar sealing, which is arranged between thecompressor block and the housing of the suction muffler and covers thesurface of the compressor block at least in the area of the mufflingchamber. In the latter case, the heat transfer from the relatively hotbasis, namely the compressor block, to the suction gas in the mufflingchamber is reduced.

[0016] Preferably, the valve package and the inner limiting wall have amutually adapted groove-projection geometry, which serves as positioningaid. Thus, the purpose of the inner limiting wall is no longerrestricted to keeping the valve package in the right position inside thehousing of the suction muffler. The groove-projection geometry alsopermits a positioning of the valve package in a predetermined angularposition in relation to the housing. For example, projections can beformed on the limiting wall, which project into grooves on the valvepackage. On the other hand, it is also possible to provide the valvepackage with projections and to provide corresponding grooves in theinner limiting wall.

[0017] Preferably, the groove-projection geometry is made to beasymmetrical. Thus, it can be ensured that the valve package can only beinserted with a predetermined angular alignment in relation to thehousing. Firstly, this simplifies the mounting. Secondly, the angularposition of the valve package in relation to the housing can bedetermined so that the most optimal path for the suction gas or thedischarge gas, respectively, appears.

[0018] Preferably, the compressor has a cylinder with a front sidefixing surface, which has the same outer contour as the valve packageand is adopted in the housing. Thus, not only the valve package isadopted in the housing, or rather, in the inner limiting wall, but theinner limiting wall is extended so much that it also surrounds thecylinder in the area of the fixing face. This gives several advantages.Firstly, the position of the valve package in relation to the cylinderis even more accurately fixed. The cylinder and the valve package areretained by the same positioning aid. Secondly, also the suction muffleris better fixed on the compressor block, primarily with regard tolateral loads.

[0019] Preferably, the fixing surface is made on a circumferentialflange. This saves material, that is, the overall wall thickness of thecylinder can be kept smaller.

[0020] Preferably, the inner limiting wall has an extension, whichcorresponds to the total height of the valve package plus the thicknessof the flange. Thus, it is possible to make the inner limiting wall reston the compressor block.

[0021] This particularly applies, when the flange rests on thecompressor block with the side facing away from the valve package. Inthis case, the cylinder is positioned in a simple manner in the axialdirection in relation to the compressor block.

[0022] Preferably, the inner limiting wall has at least one opening, andthe valve package has at least one suction gas channel extending in theradial direction. Thus, the suction gas enters through the opening intothe chamber, which is surrounded by the inner limiting wall. Here, thevalve package is arranged, which is also enclosed relatively tightly bythe inner limiting wall. As, however, the valve package has one or moreradially extending suction gas channels, the gas sucked in has noproblems in reaching the suction gas channel and the compression chamberof the compressor via the opening in the inner limiting wall, whichoverlaps the radial suction gas channel. Additionally, the radiallyextending suction gas channel has the advantage that it is easier toseparate the suction gas from the discharge gas. This again causes thata heat transfer from the discharge gas to the suction gas is reduced,which improves the efficiency of the compressor. Further, it is nolonger necessary to lead the suction gas channel(s) and the dischargegas channel(s) through both a valve plate and a retainer element, whichserves the purpose of limiting the opening movement of the discharge gasvalve. Thus, a larger cross-sectional area is available for a dischargegas opening, which again has a favourable effect on the flow behaviourof the discharge gas.

[0023] Preferably, at least one baffle is arranged in the area of theopening. The baffle or baffles, which can, for example, extend from thecovering, serve the purpose of deflecting the suction gas flow in thedirection of the opening, preferably so that the suction gas meets thevalve package substantially from the radial direction.

[0024] Preferably, a front side of the housing has a concavity, whichonly extends over a part of the width of the housing. At this step orconcavity, a recess exists in the housing, which can serve the purposeof adopting a suction connection. On the one hand, this gives room forthe suction connection; on the other hand, the volume of the mufflingchamber of the suction muffler remains large, without requiring anenlargement of the outer dimensions of the compressor housing.

[0025] It is preferred that the concavity has the shape of a lying halfcylinder; the front side of said half cylinder having a muffler inletopening. The half cylinder is relatively easily adaptable to thecylinder shape of a suction connection. The volume of the mufflingchamber is not substantially reduced.

[0026] Preferably, a baffle arrangement is arranged opposite to themuffler inlet opening inside the housing. The baffles of this bafflearrangement guide the suction gas sucked in by the suction connection inthe direction of the openings in the inner limiting wall and reduce theflow resistance of the suction muffler. At the same time, the bafflearrangement has a certain oil separation effect. A share of the oilparticles carried along by the suction gas flow cannot follow thedeflection and will therefore deposit on the surface of the bafflearrangement. Separated oil can leave the muffling chamber through an oiloutlet opening in the outer sidewall and get to an oil sump, which isformed inside the compressor housing.

[0027] Preferably, the muffler inlet opening on the outside of thehousing is surrounded by an annular wall. Also with small movements,this permits keeping the suction connection in close contact with theoutside of the suction muffler. This is particularly favourable, whenthe corresponding bearing surface of the suction connectionsubstantially corresponds to the surface of a ball section and forms aball joint with the suction muffler.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In the following, the invention is described in detail on thebasis of a preferred embodiment in connection with the drawings,showing:

[0029]FIG. 1 a vertical section through a refrigerant compressor

[0030]FIG. 2 an exploded bottom view of the elements of the cylinderhead arrangement

[0031]FIG. 3 top view a suction muffler with mounted cylinder head coverand inserted retainer element

[0032]FIG. 4 a section B-B according to FIG. 3

[0033]FIG. 5 a bottom view of the suction muffler according to FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034]FIG. 1 shows a longitudinal section through a refrigerantcompressor 1, which is arranged in a compressor housing 2. Therefrigerant compressor 1 has a compressor block 3, which carries acylinder 4. In the cylinder 4 is a piston 5 arranged to be movable, saidpiston 5 being driven by a motor 6 via a connecting rod 7. Together withthe cylinder 4, the piston 5 delimits a compression chamber 8, in whichsucked in refrigerant gas is compressed, when the piston 5 moves to theleft (in relation to the view in FIG. 1).

[0035] For controlling a gas flow into the compression chamber 8 isprovided a valve plate 9, which has (FIG. 2) two suction openings 10(only one shown) and a discharge opening 11. On the side of the valveplate 9 facing the cylinder 4 is arranged a suction valve plate 12,which has a valve leaf 13 for each suction opening 10. The valve leaf 13is formed in the suction valve plate 12 by means of punching. Usually itis arranged in the level of the suction valve plate 12, that is, itbears on the valve plate 9. Only when gas is sucked in through thesuction opening 10, the valve leaf 13 is lifted from the valve plate 9,permitting the gas to pass. When the piston 4 performs a pressurestroke, the valve leaf 13 is brought to bear on the valve plate 9 again.

[0036] In a similar manner, a discharge valve plate 14 is arranged onthe side of the valve plate 9 facing away from the suction valve plate12, said discharge valve plate 14 having a valve leaf of a dischargevalve (not shown in detail). In order to limit the movement of the valveleaf of the discharge valve plate 14, a retainer element 15 is provided.

[0037] Together, the suction valve plate 12, the valve plate 9, thedischarge valve plate 14 and the retainer element 15 form a valvepackage 16. All parts of the valve package 16 have the same outerdimensions. Preferably, they are circular and have the same diameter.

[0038] Together with a suction muffler 18 and a cylinder head cover 19,the valve package 16 forms a cylinder head 17. The cylinder head cover19 is made of a material with high heat conductivity, particularly ametal. It delimits a discharge chamber 20, which receives gas throughthe discharge opening 11, when the piston 5 reduces the compressionchamber 8, that is, exposes the gas to pressure. The cylinder head cover19 has an outlet opening 21, through which the compressed gas can bedischarged.

[0039] The suction muffler 18 has a housing 22, which has an outerlimiting wall 23 and a covering 24. The covering 24 has a recess 25, inwhich the cylinder head cover 29 is arranged. The inner diameter of therecess 25 is somewhat larger than the outer diameter of the cylinderhead cover 19, or rather, than the outer diameter of a flange 26, whichprojects radially from the cylinder head cover 19. Thus, it is avoidedthat the cylinder head cover 19 with its flange 26 touches the housing22 laterally. On the contrary, the contact between the cylinder headcover 19 and the housing 22 is limited to the bearing surface of thecylinder head cover 19 on the housing 22.

[0040] On the side opposite the cylinder head cover 19, an innercircumferential wall 27 extends from the bottom of the recess 25.

[0041] In the recess 25 is provided an opening 28, through which thecylinder head cover 19, or rather, the discharge chamber 20 formed inthe cylinder head cover 19, is connected with the valve package 16.

[0042] In its flange 26, the cylinder head cover 19 has several openings29 distributed in the circumferential direction. Corresponding openings30 are also formed in the parts of the valve package 16. The cylinder 4has a circumferential flange 31, which also has openings 32. Theopenings 29, 30, 32 can be brought in alignment with each other. Fixingbolts can be inserted through these openings. Corresponding throughholes 34 are provided in the bottom 33 of the recess 25, through whichcorresponding fixing bolts can be inserted. The openings 29, 30, 32 andthe holes 34 are so large that the corresponding fixing bolts do nothave to touch the parts of the valve package 16, the flange 31 or thehousing 22. Other components are provided for the alignment of theparts.

[0043] This can, for example, be seen from FIG. 5. On the inner limitingwall, projections 35, 36 project radially inward. The projections 35, 36are arranged to be asymmetrical, that is, the projection 36 has a largerradial extension than the projection 35. In the parts of the valvepackage 16 and in the cylinder flange 31 corresponding grooves 37 areprovided, which engage with the projections 35, 36, when the valvepackage 16 and the cylinder flange 31 are inserted in the housing 22.Thus, initially, the parts 12, 9, 14, 15 of the valve package 16 areretained by the inner limiting wall 27. These parts all have a circularshape. The inner limiting wall 27 encloses a corresponding, circularchamber. Thus, the valve package 16 is guided on all sides. Thecooperation of the projections 35, 36 with the grooves 37 causes anangle alignment of the valve package 16 or its parts 12, 9, 14, 15,respectively, in relation to each other and in relation to the housing22 of the suction muffler 18.

[0044] Corresponding grooves 38 are also provided on the flange 26 ofthe cylinder head cover 19, so that also the cylinder head cover 19 canbe mounted with a predetermined alignment in relation to the valvepackage 16 and the housing 22 of the suction muffler 18. This givesadvantages with regard to assembly techniques.

[0045] Thus, the suction muffler 18 is arranged between the cylinderhead cover 19 and the valve package 16. The valve package 16 can thuseither be inserted in the chamber inside the inner limiting wall 27 inthe assembled state or the individual parts can be inserted one afterthe other.

[0046] On the side facing the valve plate 9, the flange 31 of thecylinder 4 forms a bearing surface for the valve package 16. The innerlimiting wall 27 extends so far in the direction of the compressor block3 that also the thickness of the flange 31 is still within the innerlimiting wall 27.

[0047] As can be seen from FIG. 4, the outer limiting wall 23 extendssomewhat farther than the inner limiting wall 27 (in FIG. 4 both wallsextend to the left). On the outer limiting wall 23 is arranged acircumferential sealing 39. This sealing 39 is brought to rest on thecompressor block 3. When the housing of the suction muffler 18 is merelyplaced on the compressor block 3, the inner limiting wall 27 still has asmall distance to the surface of the compressor block. The covering ofthe housing 22 of the suction muffler 18 is to some extent flexible, sothat by means of a fixing bolt 40, with which the suction muffler 18 isfixed on the compressor block 3, it can be ensured that also the innerlimiting wall 27 bears on the compressor block 3. A muffling chamber 41,which is formed between the inner limiting wall 27 and the outerlimiting wall 23, is thus sealed on its complete boundary.

[0048] As can be seen from FIG. 1, the flange 31 in the mounted statealso bears on the compressor block 3. The cylinder 4 is led through thecompressor block 3 from the side facing away from the motor 6. Also thissimplifies the assembly. By means of the circumferential flange 31 ofthe cylinder 4, the suction muffler 18 is additionally secured on thecompressor block 3 against displacement movements.

[0049] As is particularly obvious from the FIGS. 2 and 5, the innerlimiting wall 27 has two gaps 42 or openings, which, in a manner ofspeaking, form the outlet from the muffling chamber 41. In front of thegaps 42, baffles 43 are arranged, which direct a refrigerant flow intothe gaps 42 in the inner limiting wall 27. These baffles 43 improve theflow properties.

[0050] As shown schematically in FIG. 5, the valve package 16 hassubstantially radially extending suction channels 44, which are formedby recesses 45 in the retainer element 15 and the valve plate 9 (notvisible in FIG. 2) as well as a cut-away 46 in the discharge valve plate14. Thus, the suction channel 44 extends between the retainer element 15and the valve plate 9. The retainer element 15 separates the suctionchannel 44 from the discharge chamber 20, so that a heat transfer fromthe compressed discharge gas to the suction gas sucked in is impeded.Additionally, it is possible to make the retainer element 15 of amaterial with poor heat conductivity, for example a ceramic material. Inthis case, the heat transfer from the hot discharge gas to the coldersuction gas is further impeded.

[0051] At one end, the housing 22 of the suction muffler 18 has aconcavity, in which a connection element 48 to a suction connection 49can be arranged (FIG. 1). In the cross-section, said concavity 47 hasthe shape of a half cylinder, so that here the cylinder-shapedconnection element 48 is arranged at a certain distance. The concavity47 does not extend over the whole width of the housing 22. Thus, thevolume of the muffling chamber remains relatively large. The connectionelement 48 has a substantially ball shaped front side 50, which bears onan annular wall 51, which surrounds a muffler inlet opening 52. Theannular wall 51 can be surrounded by an additional annular wall 53,which projects further from the housing and serves as an additionalprotection against oil, which runs off from the housing.

[0052] As can be seen from the FIGS. 2 and 5, a baffle arrangement 54with two baffles 55 is arranged opposite the muffler inlet opening 52,which baffle arrangement 54 guides a gas flow, which enters the mufflingchamber 41 through the muffler inlet opening 52, in the direction of thebaffles 43 in front of the gaps 42 of the inner limiting wall 27.Additionally, the baffles 55 serve the purpose of an oil separation. Ashare of the oil particles carried along by the suction gas flow cannotfollow the deflection. They settle on the surface of the baffles 55. Oilseparated in this manner can flow off from the muffling chamber 41through an opening 56 in the outer limiting wall 23, into an oil sump,which is not shown in detail, which is arranged inside the compressorhousing 2.

[0053] The bottom 33 of the recess 25 of the housing 22 is relativelythin. During assembly, this area is fixed between the cylinder headcover 19 and the retainer element 15 of the valve package 16. As it isrelatively flexible, it practically acts as a sealing between thedischarge chamber 20 in the cylinder head cover 19 and the mufflingchamber 41 of the suction muffler 18.

[0054] Instead of the lip seal 39 shown in FIG. 4, which is moulded ontothe outer limiting wall 23, of course a sealing can also be used, whichis formed as a separate component. Also a planar sealing (not shown) canbe used, which is arranged between the compressor block 3 and thesuction muffler 18 or the flange 31, respectively, and covers thecompressor block 3 at least in the area of the muffling chamber 41. Withsuch a sealing, the heat transfer from the relatively hot basis of thecompressor block 3 to the suction gas in the muffling chamber 41 isreduced.

[0055] The fact that the valve block 16 is arranged inside the suctionmuffler 18 causes that the muffling chamber 41, which is limited by theouter limiting wall 23, the inner limiting wall 27, the covering 24 andthe compressor block 3, does not only muffle noises which occur in thesuction gas flow, the suction muffler 18 can also reduce mechanicalnoises from the valve package 16.

[0056] In order to avoid flow noises and flow losses, the limits of allopenings and channels are rounded, that is, for example the edges of thesuction opening 10 and the discharge opening 11 as well as the edges ofthe gaps 42.

[0057] In a manner not shown in detail, the flange 26 of the cylinderhead cover 19 can additionally be provided with a circumferentialprojection projecting in the axial direction. This projection increasesthe rigidity of the complete cover. Further, it offers a larger heatemission surface, so that the gas in the discharge chamber 20 can becooled faster.

What is claimed is:
 1. A cylinder head arrangement for a pistoncompressor, particularly a hermetically enclosed refrigerant compressor,with a suction muffler and a valve package having a valve plate, atleast one suction valve and at least one discharge valve, wherein thesuction muffler has a housing, in which the valve package is adopted,the housing having positioning means, which determine the position ofthe valve package in the housing.
 2. An arrangement according to claim1, wherein the suction muffler is arranged between the valve package anda cylinder head cover.
 3. An arrangement according to claim 2, whereinthe housing has an outer limiting wall and a covering, which has arecess, in which the cylinder head cover is arranged.
 4. An arrangementaccording to claim 3, wherein the recess has a bottom, which is providedwith an opening, through which the valve package is connected with acavity formed on the inside of the cylinder head cover.
 5. Anarrangement according to claim 3, wherein the cylinder head cover has anouter diameter, which is smaller than the inner diameter of the recess.6. An arrangement according to claim 1, wherein an inner limiting wall,which surrounds the valve package, extends from the covering.
 7. Anarrangement according to claim 6, wherein the inner limiting wallextends from the bottom of the recess.
 8. An arrangement according toclaim 6, wherein in the direction of a compressor block, the innerlimiting wall projects less than the outer limiting wall, the coveringbeing so flexible that also the inner limiting wall can be brought torest on the compressor block by means of a clamping arrangement.
 9. Anarrangement according to claim 7, wherein the outer limiting wall isprovided with a sealing, which is meant to rest on the compressor block.10. An arrangement according to claim 6, wherein the valve package andthe inner limiting wall have a mutually adapted groove-projectiongeometry, which serves as positioning aid.
 11. An arrangement accordingto claim 10, wherein the groove-projection geometry is made to beasymmetrical.
 12. An arrangement according to claim 1, wherein thecompressor has a cylinder with a front side fixing surface, which hasthe same outer contour as the valve package and is adopted in thehousing.
 13. An arrangement according to claim 12, wherein the fixingsurface is made on a circumferential flange.
 14. An arrangementaccording to claim 13, wherein the inner limiting wall has an extension,which corresponds to the total height of the valve package plus thethickness of the flange.
 15. An arrangement according to claim 13,wherein the flange rests on the compressor block with the side facingaway from the valve package.
 16. An arrangement according to claim 6,wherein the inner limiting wall has at least one opening, and the valvepackage has at least one suction gas channel extending in the radialdirection.
 17. An arrangement according to claim 16, wherein at leastone baffle is arranged in the area of the opening.
 18. An arrangementaccording to claim 1, wherein a front side of the housing has aconcavity, which only extends over a part of the width of the housing.19. An arrangement according to claim 18, wherein the concavity has theshape of a lying half cylinder, the front side of said half cylinderhaving a muffler inlet opening.
 20. An arrangement according to claim19, wherein a baffle arrangement is arranged opposite to the mufflerinlet opening inside the housing.
 21. An arrangement according to claim19, wherein the muffler inlet opening on the outside of the housing issurrounded by an annular wall.